1. Field of the Invention
The invention relates to the field of apparatus for discharging a substance, and more particularly, to an apparatus having rotatable vanes, which is operable to impart centrifugal force to the substance, such that the substance is discharged at increased velocity and in a path of desired orientation and divergence.
2. Prior Art
Devices are known for imparting a centrifugal force to a fluid or granular substance or to a slurry of both, in order to discharge the substance at an increased velocity. Such devices typically include a rotatable impeller wheel having a number of radially oriented vanes. The fluid or granular substance is introduced at a central portion of the wheel and is collected by the vanes as the wheel rotates. Each portion of the substance follows a spiral path and is ejected from the impeller at the vane tips. The portion is emitted in the plane of the impeller vanes at a tangent to its spiral path. Relative to the impeller the substance has a tangential velocity component and a radial velocity component. The relationship of the radial and tangential components, and the timing of emission into the impeller and travel along the vanes, determine the particular angle relative to the impeller at which each portion of the substance is directed.
Centrifugal discharge devices are disclosed in U.S. Pat. Nos. 421,729 (Kisinger); 2,936,563 (Blume); and 4,541,566 (Kijima et al). These patents each disclose a device for developing a liquid spray around the entire circumference of a rotating apparatus. More specifically, these devices are intended to produce a spray around their entire circumference in order to dispense the liquid in all directions from the point of discharge into the impeller.
For certain applications, however, a liquid spray directed over a limited angle is desirable. U.S. Pat. No. 3,625,430 (Arnold et al) discloses a rotary liquid spray generator which is intended to produce a liquid spray over a limited angle. The spray generator has a plurality of blades arranged radially on a rotatable ring. A liquid supply pipe is centrally located within the rotatable ring and has an opening which directs a stream of the liquid radially outwardly, where it is encountered by the blades. The liquid spray is claimed to be generated over an angle approximately equal to the angle of the opening; however it is difficult or impossible in a device of this kind to obtain any precise control of the liquid spray pattern. According to Arnold the device is intended to produce a fine spray for wetting dust particles intersecting the spray, and the device is not suitable for producing a spray wherein substantial velocity is to be imparted to the liquid substance.
It is known to confine the discharge of a rotary impeller by enclosing the impeller in a housing which has an axial inlet to the impeller and an outlet nozzle directed tangentially along a peripheral edge. Such devices confine the output but do not permit adjustment of the spray pattern over different angles and in different directions (at least not without repositioning the housing and/or varying the character of the nozzle). Nor do such devices efficiently use the energy of the impeller to impart velocity to the spray. The radial velocity and the tangential velocity produced by the impeller at points other than at the ends of the blades approaching the outlet nozzle are wasted because the liquid is confined by the housing leading to the outlet nozzle.
A centrifugal spray device which develops a spray in a precise and controllable angular spray pattern without using a nozzle or similar confining structure would be advantageous in that it would more efficiently utilize the energy of the impeller and its motor or other drive means. Provided the impeller of such a device can be arranged to direct the sprayed substance along the desired outlet path only, the impeller can develop a more forceful spray than a comparable device wherein the spray is confined to a desired outlet path by fixed structures which interfere with the flow of the substance while guiding the substance to the outlet.
The invention provides a centrifugal spray apparatus which generates a spray in a precise angular pattern. The apparatus produces a spray similar to that produced by a centrifugal or tangential nozzle, without directing the sprayed substance against fixed interfering structures, thereby imparting a high velocity to the substance while reducing scattering. The invention allows for adjustment of the substance spray pattern over different angles and in different directions.